Observe selected HTTP status codes

Prediction

Changing the exact status changes the response semantics even when the client and target stay the same. A HEAD request should expose metadata without response content.

Controlled observation

Select one reviewed fixed response for 200, 404, or 429, or issue HEAD for the fixed 404. The result shows status, fields, and bounded content separately.

Explanation

The first digit gives a class, while the complete code defines the result. An application message cannot redefine that HTTP meaning.

HTTP/1.1 200 OK
Content-Type: application/json
X-Lab-Scenario: status

{"scenario":"status","status":200}

'curl' '--include' '--request' 'GET' 'https://lab.httpclarity.com/v1/status/200'

const response = await fetch("https://lab.httpclarity.com/v1/status/200", {
  "method": "GET"
});
console.log(response.status, await response.text());

<?php
$options = ['http' => [
    'method' => 'GET',
    'ignore_errors' => true,
]];
$context = stream_context_create($options);
$body = file_get_contents('https://lab.httpclarity.com/v1/status/200', false, $context);
var_dump($http_response_header, $body);